1. ACI 550.2R-13
Design Guide for Connections in
Precast Jointed Systems
Reported by Joint ACI-ASCE Committee 550

2. First Printing
April 2013
American Concrete Institute®
Advancing concrete knowledge
Design Guide for Connections in Precast Jointed Systems
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3. ACI 550.2R-13
Design Guide for Connections in Precast Jointed
Systems
Reported by Joint ACI-ASCE Committee 550
Thomas J. D’Arcy, Chair
Te-Lin Chung
Ned M. Cleland
William K. Doughty
Alvin C. Ericson
Melvyn A. Galinat
Harry A. Gleich
Mohammad S. Habib
Neil M. Hawkins
Augusto H. Holmberg
L. S. Paul Johal
Jason J. Krohn
Emily B. Lorenz
Kenneth A. Luttrell
Vilas S. Mujumdar
Frank A. Nadeau
Clifford R. Ohlwiler
Victor F. Pizano-Thomen
Jose I. Restrepo
Sami H. Rizkalla
Mario E. Rodriguez
Joseph C. Sanders
John F. Stanton
P. Jeffrey Wang
Cloyd E. Warnes
3.5—Debonding, p. 7
The proper detailing and design of precast concrete connections
are essential to the performance of a precast concrete structure.
This guide provides information on design, detailing, and construction of connections between precast members in jointed systems,
including moment frame and structural wall systems.
CHAPTER 4—PRECAST CONCRETE FLOOR
SYSTEMS, p. 7
4.1—Precast systems, p. 7
4.2—Precast floor diaphragms, p. 7
Keywords: bolting; connection; debonding; ductility; erection; moment
frame; precast; pretopped; post-tensioning; structural walls; welding.
CHAPTER 5—LATERAL-LOAD-RESISTING
SYSTEMS, p. 8
5.1—Structural walls, p. 8
5.2—Structural walls with large openings, p. 8
5.3—Moment frames, p. 8
CONTENTS
CHAPTER 1—INTRODUCTION AND SCOPE, p. 2
1.1—Introduction, p. 2
1.2—Scope, p. 2
CHAPTER 6—CONNECTIONS, p. 10
6.1—Strength, p. 10
6.2—Ductility, p. 10
6.3—Volume change accommodation, p. 11
6.4—Durability, p. 11
6.5—Fire resistance, p. 11
6.6—Constructibility, p. 11
6.7—Aesthetics, p. 11
6.8—Seismic requirements, p. 11
6.9—Tolerances, p. 11
6.10—Vertical connections, p. 11
CHAPTER 2—NOTATION AND DEFINITIONS, p. 2
2.1—Notation, p. 2
2.2—Definitions, p. 2
CHAPTER 3—GUIDELINES FOR DESIGN, p. 3
3.1—Classes of connections, p. 3
3.2—Principles of connection design, p. 3
3.3—Anchorage to concrete, p. 5
3.4—Welding, p. 5
ACI Committee Reports, Guides, and Commentaries are
intended for guidance in planning, designing, executing, and
inspecting construction. This document is intended for the use
of individuals who are competent to evaluate the significance
and limitations of its content and recommendations and who
will accept responsibility for the application of the material it
contains. The American Concrete Institute disclaims any and
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Reference to this document shall not be made in contract
documents. If items found in this document are desired by
the Architect/Engineer to be a part of the contract documents,
they shall be restated in mandatory language for incorporation
by the Architect/Engineer.
CHAPTER 7—ERECTION CONSIDERATIONS, p. 13
CHAPTER 8—WELDING CONSIDERATIONS, p. 13
8.1—Steel assemblies, p. 13
ACI 550.2R-13 was adopted and published April 2013.
Copyright © 2013, American Concrete Institute.
All rights reserved including rights of reproduction and use in any form or by any
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1

4. 2
DESIGN GUIDE FOR CONNECTIONS IN PRECAST JOINTED SYSTEMS (ACI 550.2R-13)
8.2—Galvanized steel, p. 13
8.3—Stainless steel, p. 14
8.4—Reinforcement, p. 14
8.5—Welding practices for epoxy-coated material, p. 15
CHAPTER 9—GROUTING, p. 15
CHAPTER 10—REFERENCES, p. 15
CHAPTER 1—INTRODUCTION AND SCOPE
1.1—Introduction
Precast concrete structural systems are composed of individually fabricated components. Because of the segmental
nature of precast concrete construction, connections between
individual components are required to support the design
loads. Connections are also required to accommodate deformations, including rotations and strains.
1.1.1 Connection methods—Precast components are
connected by one of two methods. The first method connects
components by reinforcement that protrudes from each
component end, spliced using proprietary hardware or by
lap-splicing with a small quantity of cast-in-place concrete
to complete the connection. This method is referred to as
emulation, or a wet connection, because it involves fieldplaced cast-in-place concrete and mimics the behavior of
cast-in-placed monolithic structures. The second, morecommon, method of connection is dry and connects components by welding, bolting, post-tensioning, or doweling
without using field-placed concrete. Because dry connections are typically less stiff than their connecting precast
components, deformations tend to be concentrated in the
connections.
Connections should allow for easy and economical
component casting and assembly, fabrication, erection clearance, and erection tolerances. They should also tolerate
anticipated deformation without significant loss of strength.
1.1.2 Connection groups—Connections are categorized
into five groups:
1) Gravity load transfer—Gravity loads alone, such as
hollow core members placed on a beam ledge
2) Shear transfer—Either vertical shear, horizontal shear,
or both, such as a double-tee flange-to-flange connection
3) Moment transfer—The tension and compression
forces created by moment, such as a connection between a
precast moment frame and its foundation
4) Structural integrity—Code-prescribed structural
integrity forces; typically a connection with combination
accommodations
5) Combination connection—A combination of loads,
such as moments and shear
In all cases, the load paths and external loads are accommodated in all elements of connections (Fig. 1.1.2).
Tying all precast members to each adjacent member is
essential for structural integrity as required by Chapter 16
of ACI 318-11. Such connections, however, should not be so
rigid as to prevent member rotation or volume change strains
when required.
Fig. 1.1.2—Wall panel to foundation connection.
1.2—Scope
This guide provides information on the characteristics and
design of connections between precast concrete components
and between precast components and cast-in-place construction. The proper detailing and design of precast concrete
connections are essential to the performance of a precast
concrete structure.
This guide describes typical precast jointed systems and
their connection types, performance, and characteristics,
and provides recommendations for design and construction. Three classes of connections are identified and their
characteristic and key design considerations given. Also
included are guidelines for designing connections and their
anchorage, a description of precast systems, typical lateralload-resisting systems, key design considerations, and erection requirements including special welding considerations.
CHAPTER 2—NOTATION AND DEFINITIONS
2.1—Notation
Cd = deflection amplification factor
fc′ = specified compressive strength of concrete, psi
(MPa)
R = response modification factor
f = strength reduction factor
2.2—Definitions
ACI provides a comprehensive list of definitions through
an online resource, “ACI Concrete Terminology,” http://
terminology.concrete.org. Definitions provided herein
complement that resource.
deformable connection—a class of connection between
precast members designed to either display significant flexibility or to yield, without losing strength, when subjected to
expected deformations.
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